Silicone composition and polysiloxane compound

Abstract

Provided are a silicone composition and a polysiloxane compound which make it possible to suppress an increase in the hardness of the silicone composition when left for a long period of time at a high temperature. A silicone composition according to the present invention comprises: (A) a linear organopolysiloxane having one structure of a metal salt of a dicarboxylic acid at a main-chain terminal thereof; (B) a filler; and (C) a silicone resin.

Description

Silicone composition and polysiloxane compound

[0001] The present invention relates to a polysiloxane compound and a silicone composition containing the same.

[0002] As semiconductor devices become higher in capacity and density, they are required to have high heat dissipation capabilities. In recent years, thermally conductive materials called thermal interface materials have been placed between semiconductor devices, such as IC chips, which are heat-generating components, and heat sinks or housings, which are cooling components, to efficiently dissipate heat generated by the semiconductor devices to the outside.

[0003] One type of thermal interface material is a thermally conductive silicone composition, which is made by mixing a thermally conductive filler with a silicone resin, due to its excellent heat resistance and rubber properties. Thermally conductive silicone compositions are generally curable, and their properties are effectively exerted by curing after being applied or placed in the desired location.

[0004] Incidentally, the higher the filling rate of the thermally conductive filler in a thermally conductive silicone composition, the better the heat dissipation properties, so it is preferable to fill as much as possible. On the other hand, if the filling rate is increased, the thermally conductive silicone composition may become too hard. In particular, the hardness of a cured product of the thermally conductive silicone composition tends to continue to increase even after curing is complete when left at high temperatures for a long period of time. Excessive hardness of the thermally conductive silicone composition makes it more susceptible to cracking. If cracks occur in the thermally conductive silicone composition, gaps will form, which may prevent the desired heat dissipation properties from being achieved.

[0005] In response to this, Patent Document 1 provides a curable organopolysiloxane composition that has a high filling rate of a thermally conductive filler and is capable of suppressing an increase in hardness even when aged for a long period of time under high-temperature conditions. The curable organopolysiloxane composition of Patent Document 1 contains, in addition to an organopolysiloxane, at least one selected from a fatty acid, a fatty acid ester, and a fatty acid metal salt.

[0006] WO2022 / 215510

[0007] However, due to the recent trend toward ever higher capacities in semiconductor devices, more reliable heat dissipation properties have become important, and therefore there is a demand for organopolysiloxane compositions that can further suppress increases in hardness compared to the organopolysiloxane composition of Patent Document 1.

[0008] An object of the present invention is to provide a silicone composition that can suppress an increase in hardness when left at high temperatures for an extended period of time in a composition containing a filler and a silicone resin, and a polysiloxane compound used therein.

[0009] In order to solve the above problems, the present invention includes the following inventions.

[0010] The present invention [1] includes a silicone composition containing (A) a linear organopolysiloxane having one dicarboxylate metal salt structure at the terminal of its main chain, (B) a filler, and (C) a silicone resin.

[0011] The present invention [2] includes the silicone composition according to [1], in which the structure of the metal dicarboxylate is a group represented by the following formula (1) or (2):

[0012]

[0013] (In formulas (1) and (2), M ｄ＋ represents an alkali metal ion or an alkaline earth metal ion. a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less. d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal. e is 2 when M is an alkali metal, and 1 when M is an alkaline earth metal. f is an integer of 0 or more and 10 or less, g is an integer of 0 or more and 5 or less, and h is an integer of 0 or more and 5 or less.

[0014] The present invention [3] includes the silicone composition according to [1] or [2], wherein the content of the filler in the silicone composition is 70 mass % or more.

[0015] The present invention [4] includes the silicone composition according to any one of [1] to [3], wherein the filler is a thermally conductive filler.

[0016] The present invention [5] includes the silicone composition according to any one of [1] to [4], wherein the silicone resin is a curable silicone resin.

[0017] The present invention [6] includes the silicone composition according to [5], in which the curable silicone resin contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane.

[0018] The present invention [7] includes a silicone cured product obtained by curing the silicone composition according to [5] or [6].

[0019] The present invention [8] includes an electronic component comprising a heat-generating component, a cooling component, and the silicone composition according to any one of [1] to [6] or the silicone cured product according to [7], which is arranged so as to be in contact with the heat-generating component and the cooling component.

[0020] The present invention [9] includes a polysiloxane compound represented by the following formula (5):

[0021] (In formula (5), R １ represents a hydrocarbon group, and R ２ represents a hydrocarbon group; n is an integer of 1 or more and 100 or less; and A is a group represented by the following formula (1) or (2):

[0022]

[0023] (In formulas (1) and (2), M ｄ＋ represents an alkali metal ion or an alkaline earth metal ion. a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less. d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal. e is 2 when M is an alkali metal, and 1 when M is an alkaline earth metal. f is an integer of 0 or more and 10 or less, g is an integer of 0 or more and 5 or less, and h is an integer of 0 or more and 5 or less.

[0024] The silicone composition and polysiloxane compound of the present invention can suppress an increase in hardness of the silicone composition when left at high temperatures for an extended period of time.

[0025] FIG. 1 shows a schematic cross-sectional view of a semiconductor device of the present invention. FIG. 2 shows an IR spectrum of the one-terminal succinic anhydride-modified polysiloxane prepared in Synthesis Example 1. FIG. 3 shows an IR spectrum of the one-terminal lithium succinate-modified polysiloxane prepared in Synthesis Example 1. FIG. 4 shows an IR spectrum of the one-terminal lithium succinate-modified polysiloxane prepared in Synthesis Example 2. FIG. 5 shows an IR spectrum of the one-terminal calcium succinate-modified polysiloxane prepared in Synthesis Example 3. FIG. 6 shows an IR spectrum of the one-terminal lithium monocarboxylate-modified polysiloxane prepared in Synthesis Example 5.

[0026] An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiment described below, and can be implemented by modifying it as desired without departing from the gist of the present invention.

[0027] The silicone composition of the present invention (hereinafter also referred to as "the composition") contains (A) a linear organopolysiloxane having one dicarboxylate metal salt structure at the end of its main chain (hereinafter also referred to as "the polysiloxane"), (B) a filler, (C) a silicone resin, and any other optional components. These are described below.

[0028] (A) The Present Polysiloxane The present polysiloxane is a linear organopolysiloxane having one dicarboxylate metal salt structure at one end of its main chain. In other words, the present polysiloxane is an organopolysiloxane having a dicarboxylate metal salt structure at one end.

[0029] The structure of a metal salt of dicarboxylic acid is a functional group having the main skeleton of a metal salt of dicarboxylic acid, specifically a group in which one hydrogen atom has been removed from a metal salt of dicarboxylic acid.

[0030] Examples of dicarboxylate metal salts include malonate, succinate, glutarate, adipate, pimelate, suberate, sebacate, phthalate, 2,2'-biphenyldicarboxylate, 1,4-cyclohexanedicarboxylate, bicyclo[2.2.1]heptane-2,3-dicarboxylate, etc. Preferred are malonate, succinate, glutarate, and bicyclo[2.2.1]heptane-2,3-dicarboxylate.

[0031] Examples of metal salts constituting the dicarboxylic acid metal salt include alkali metal salts such as lithium salt, sodium salt, and potassium salt; and alkaline earth metal salts such as magnesium salt, calcium salt, and barium salt. Preferably, alkali metal salts are used, and more preferably, lithium salts are used.

[0032] The structure of the dicarboxylic acid metal salt is preferably a group represented by the following formula (1) or (2).

[0033]

[0034] In formulas (1) and (2), M ｄ＋ represents an alkali metal ion or an alkaline earth metal ion.

[0035] a is, for example, an integer of 0 or more and 10 or less, preferably 1 or more, and preferably 8 or less, and more preferably 5 or less.

[0036] b is, for example, an integer of 0 or more and 3 or less, preferably 1 or more and 2 or less.

[0037] For example, c is an integer of 0 or more and 3 or less, preferably 1 or more and 2 or less.

[0038] d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal.

[0039] e is 2 when M is an alkali metal, and is 1 when M is an alkaline earth metal.

[0040] f is, for example, an integer of 0 or more and 10 or less, preferably 1 or more, and preferably 8 or less, and more preferably 5 or less.

[0041] g is, for example, an integer of 0 or more and 5 or less, and preferably 1 or more and 3 or less.

[0042] h is, for example, an integer of 0 or more and 5 or less, preferably 1 or more and 3 or less.

[0043] Among the groups represented by formula (1), a group represented by the following formula (3) is more preferred, and among the groups represented by formula (2), a group represented by the following formula (4) is more preferred. A particularly preferred structure of the dicarboxylic acid metal salt is the group represented by formula (3).

[0044]

[0045] In the formulas (3) and (4), M' is an alkali metal. Examples of the alkali metal include lithium, sodium, and potassium, and preferably lithium.

[0046] The linear organopolysiloxane portion of the present polysiloxane has a siloxane bond (—O—Si—) in the main chain and an organic group in the side chain. Preferably, the side chain does not have a siloxane bond. The organic group is, for example, a hydrocarbon group, and preferably, １ is.

[0047] The other terminal of the present polysiloxane may be, for example, a hydrocarbon group, a hydrogen atom, a vinyl group, an acryloyl group, a methacryloyl group, or a hydroxyl group. These are preferably used in the R ２ is.

[0048] A specific example of such a polysiloxane of the present invention is preferably a polysiloxane compound represented by the following formula (5).

[0049]

[0050] R １is, for example, a hydrocarbon group, and preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. １ Examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-octyl, and decyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, aryl groups such as phenyl, tolyl, and xylyl groups, aralkyl groups such as benzyl and phenethyl groups, and fluoroalkyl groups such as trifluoropropyl groups. Preferably, alkyl groups are used, and more preferably, methyl and ethyl groups are used. １ may be the same or different from each other.

[0051] R ２ is, for example, a hydrocarbon group, a hydrogen atom, a vinyl group, an acryloyl group, a methacryloyl group, a hydroxyl group, or the like, and is preferably a hydrocarbon group. These hydrocarbon groups may be substituted with a halogen atom or the like. The number of carbon atoms in the hydrocarbon group is, for example, 1 or more, preferably 3 or more, and for example, 20 or less, preferably 10 or less. R ２ Examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-octyl, decyl, dodecyl, and octadecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and naphthylmethyl; and fluoroalkyl groups such as trifluoropropyl. Preferably, an alkyl group is used, and more preferably, an n-butyl group or a methyl group is used.

[0052] n is, for example, a number from 1 to 100. Preferably, n is 10 or more, more preferably 20 or more, and preferably 90 or less, more preferably 60 or less, and even more preferably 30 or less. When n is equal to or greater than the above-mentioned lower limit, the compatibility between the present polysiloxane and the silicone resin serving as the matrix resin is improved, allowing the present polysiloxane to exhibit its functions more effectively. When n is equal to or less than the above-mentioned upper limit, the present composition has excellent fluidity.

[0053] A is a group represented by the above formula (1) or (2), preferably a group represented by formula (1), and more preferably a group represented by formula (3).

[0054] Among the polysiloxane compounds represented by formula (5), more preferred are polysiloxane compounds represented by the following formula (6) or (7), and even more preferred are polysiloxane compounds represented by formula (6).

[0055]

[0056] The content of the present polysiloxane is, for example, 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and for example, 100 parts by mass or less, preferably 80 parts by mass or less, more preferably 50 parts by mass or less, relative to 100 parts by mass of the silicone resin described below. The content of the present polysiloxane in the present composition is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and for example, 10% by mass or less, preferably 5% by mass or less.

[0057] The present polysiloxane can be produced, for example, by (1) a ring-opening polymerization step of a cyclic siloxane, (2) a hydrosilylation step, and (3) an ion exchange step.

[0058] (1) In the ring-opening polymerization step of cyclic siloxane, cyclic siloxane is subjected to ring-opening polymerization to obtain a linear polysiloxane. A known method can be used for the ring-opening polymerization of cyclic siloxane. Preferably, anionic ring-opening polymerization is carried out using an alkyllithium compound as an initiator and a silane hydride halide as a terminator. This results in a linear single-terminated Si—H polysiloxane with an Si—H bond at one end and an alkyl group bonded at the other end.

[0059] Examples of cyclic siloxanes used as raw materials include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and decamethylcyclohexasiloxane. Examples of alkyllithium compounds include methyllithium, n-butyllithium, sec-butyllithium, and tert-butyllithium. Examples of silane hydrides include chlorodimethylsilane. The reaction conditions and reagents for anionic ring-opening polymerization may be determined according to known methods.

[0060] (2) In the hydrosilylation step, a dicarboxylic acid or dicarboxylic anhydride is bonded to the linear polysiloxane obtained in the ring-opening polymerization step using a hydrosilylation reaction. Specifically, a one-terminal Si—H polysiloxane is added to a dicarboxylic acid or dicarboxylic anhydride having an unsaturated bond. This results in a one-terminal dicarboxylic acid-modified polysiloxane having a dicarboxylic acid or dicarboxylic anhydride bonded to one terminal and an alkyl group bonded to the other terminal.

[0061] Examples of the dicarboxylic acid or dicarboxylic acid anhydride having an unsaturated bond include allyl succinic anhydride and 5-norbornene-2,3-dicarboxylic anhydride.

[0062] The hydrosilylation reaction is preferably carried out using a hydrosilylation catalyst. Examples of the hydrosilylation catalyst include the same hydrosilylation catalyst (C3) described below. The hydrosilylation reaction conditions, reagents, etc. may be determined according to known methods.

[0063] In the (3) ion exchange step, the product obtained in the hydrosilylation step is subjected to ion exchange. Specifically, the H of the carboxylic acid in the one-terminal dicarboxylic acid-modified polysiloxane is exchanged with a metal ion. This results in a one-terminal dicarboxylic acid metal salt-modified polysiloxane (i.e., the present polysiloxane) having a dicarboxylic acid metal salt bonded to one terminal and an alkyl group bonded to the other terminal.

[0064] In the ion exchange step, when the one-terminal dicarboxylic acid-modified polysiloxane is an acid anhydride, it is preferable to simultaneously carry out hydrolysis. Specifically, the one-terminal dicarboxylic acid-modified polysiloxane, a lower fatty acid metal salt, and water are reacted under heating. Examples of the lower fatty acid metal salt include acetate salts and propionate salts. Examples of metal salts constituting the lower fatty acid metal salt include alkali metal salts such as lithium salts, sodium salts, and potassium salts; and alkaline earth metal salts such as magnesium salts, calcium salts, and barium salts. These metal salts may be hydrates. The heating temperature is, for example, 50°C or higher and 150°C or lower. Other reaction conditions, reagents, etc. may be selected according to known methods.

[0065] As a method other than the ion exchange step (3), a method of carrying out a neutralization reaction using a hydroxide of an alkali metal or alkaline earth metal, such as lithium hydroxide, can also be employed.

[0066] (B) Filler Examples of fillers include inorganic fillers and organic fillers. Preferably, inorganic fillers are used, and more preferably, thermally conductive fillers are used. This provides excellent thermal conductivity and makes the material suitable for use in thermal interface materials. In addition, it is possible to reliably suppress an increase in hardness due to interactions between the filler and the silicone resin.

[0067] The thermally conductive filler is an inorganic particle having good thermal conductivity, and examples thereof include alumina, zinc oxide, magnesium oxide, titanium oxide, silicon nitride, aluminum nitride, boron nitride, aluminum hydroxide, magnesium hydroxide, silicon carbide, calcium carbonate, barium sulfate, talc, silica, diamond, aluminum, silver, copper, etc. These may be used alone or in combination of two or more. From the viewpoint of excellent thermal conductivity, alumina, silicon nitride, aluminum nitride, and boron nitride are preferred, and from the viewpoint of ease of handling, alumina and aluminum nitride are preferred.

[0068] Examples of the shape of the filler include spherical shapes such as perfect spheres, polyhedral spheres, and ellipsoidal spheres; plate-like shapes, needle-like shapes, crushed shapes, aggregate shapes, and irregular shapes, and preferably spherical shapes.

[0069] The average particle size of the filler is, for example, 0.01 μm or more, preferably 0.1 μm or more, and for example, 500 μm or less, preferably 200 μm or less. In the present invention, the average particle size refers to the particle size at 50% volume similarity (D50) in a particle size distribution curve determined by laser diffraction.

[0070] In the present composition, it is preferable to use multiple fillers with different average particle sizes. For example, at least two of the following are used: a large-diameter filler with an average particle size of 50 μm or more, a medium-diameter filler with an average particle size of 10 μm or more but less than 50 μm, a small-diameter filler with an average particle size of 1 μm or more but less than 10 μm, and a microfiller with an average particle size of less than 1 μm. Preferably, three or more of the above fillers are used, and more preferably, all four of the above fillers are used. This ensures that the filler loading rate in the present composition is improved. Therefore, when a thermally conductive filler is used, the thermal conductivity of the present composition can be further improved.

[0071] The specific surface area of ​​the entire filler is, for example, 0.1 m ２ / g or more, 10m ２ / g or less. The specific surface area is measured by the BET method. In addition, the cumulative pore volume of pores having a pore diameter of 0.5 μm or less in the entire thermally conductive filler is, for example, 0.1 mL or less. The pore diameter is calculated from the maximum diameter distribution measured with a mercury porosimeter.

[0072] The filler may be treated with a surface treatment agent, etc. Examples of the surface treatment agent include known treatment agents such as silane coupling agents.

[0073] The filler content (filling rate) in the composition is, by mass, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 85% by mass or more, and even more preferably 92% by mass or more, and for example, 99% by mass or less, preferably 97% by mass or less, and more preferably 95% by mass or less. Furthermore, by volume, it is, for example, 50% by volume or more, preferably 65% ​​by volume or more, more preferably 80% by volume or more, and for example, 99% by volume or less, preferably 97% by volume or less, and more preferably 95% by volume or less. The higher the filler content, the easier it is to increase the thermal conductivity of the resin composition. The lower the filler content, the easier it is to increase the fluidity of the resin composition. From the viewpoint of the balance between thermal conductivity and fluidity, it is preferable to set the filler content to be above the lower limit and below the upper limit. In particular, when the filler content is 70% by mass or more, the filler is generally present in an overcrowded state relative to the silicone resin, which facilitates interaction between the filler and the silicone resin and makes it more likely that an increase in hardness will occur over the long term; however, the present composition can more reliably suppress this increase in hardness.

[0074] (C) Silicone Resin The silicone resin is a polymer having a siloxane bond in the main skeleton, and may be either a curable silicone resin or a non-curable silicone resin, but is preferably a curable silicone resin. This provides excellent fluidity and workability, making it suitable for use in thermal interface materials and the like.

[0075] Examples of the curable silicone resin include addition reaction type silicone resins and condensation reaction type silicone resins, and preferably addition reaction type silicone resins.

[0076] When the silicone resin is an addition reaction type silicone resin, the silicone resin contains, for example, (C1) an alkenyl group-containing organopolysiloxane and (C2) a hydrosilyl group-containing organopolysiloxane. In this case, the silicone resin may contain (C3) a hydrosilylation catalyst for causing the addition reaction, as needed. In this composition, the catalyst required for the curing reaction is contained as part of the silicone resin.

[0077] (C1) Alkenyl Group-Containing Organopolysiloxane: The alkenyl group-containing organopolysiloxane is the base resin of the silicone resin and contains alkenyl groups. Examples of the alkenyl groups include vinyl groups, allyl groups, and butenyl groups, with vinyl groups being preferred. The alkenyl groups may be bonded to the molecular chain terminals or to side chains, but from the viewpoint of reactivity, etc., it is preferable that the alkenyl groups be bonded to both molecular chain terminals.

[0078] The alkenyl group-containing organopolysiloxane may be linear, branched, or cyclic, but is preferably linear. The alkenyl group-containing organopolysiloxane may be used alone or in combination of two or more types.

[0079] The alkenyl group-containing organopolysiloxane preferably includes a polysiloxane represented by the following formula (8).

[0080]

[0081] R ３ is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of hydrocarbon groups include R １ Examples of the groups include the same groups as those exemplified in the group 1. Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used.３ may be the same or different from each other.

[0082] R ４ is an alkenyl group, as described above. ４ may be the same or different from each other.

[0083] m is, for example, a number of 0 or more and 10,000 or less, preferably 10 or more and 1,000 or less.

[0084] The viscosity of the alkenyl group-containing organopolysiloxane at 23°C is, for example, 1 mPa·s or more, preferably 10 mPa·s or more, and for example, 100,000 mPa·s or less, preferably 1,000 mPa·s or less. By adjusting the viscosity within this range, a composition having the desired physical properties can be obtained with good workability. The viscosity can be measured using an E-type viscometer. Specifically, a shear rate of 0.1 to 100 s is measured using a conical plate with a diameter of 40 mm and a cone angle of 2.0°, and a Peltier plate is used to maintain a temperature of 25°C. －１ The viscosity is measured up to a steady state value, and the value at which the viscosity reaches a steady state can be regarded as the viscosity to be measured.

[0085] (C2) Hydrosilyl Group-Containing Organopolysiloxane The hydrosilyl group-containing organopolysiloxane functions as a crosslinking agent that crosslinks base resins together, and contains hydrosilyl groups (—Si—H). The hydrosilyl groups may be bonded to the molecular chain terminals or to side chains.

[0086] The hydrosilyl group-containing organopolysiloxane may be linear, branched, or cyclic, but is preferably linear. One type of hydrosilyl group-containing organopolysiloxane may be used alone, or two or more types may be used in combination.

[0087] The hydrosilyl group-containing organopolysiloxane is preferably a polysiloxane represented by the following formula (9).

[0088]

[0089] R ５is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of hydrocarbon groups include R １ Examples of the groups include the same groups as those exemplified in the group 1. Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. ５ may be the same or different from each other.

[0090] p and q are each, for example, a number of 2 or more and 100 or less, preferably 10 or more and 50 or less.

[0091] The viscosity of the hydrosilyl group-containing organopolysiloxane at 23° C. is, for example, 1 mPa s or more, preferably 10 mPa s or more, and for example, 100,000 mPa s or less, preferably 1,000 mPa s or less. By setting the viscosity within this range, a composition having the desired physical properties can be obtained with good workability.

[0092] The mixing mass ratio of the alkenyl group-containing organopolysiloxane (C1) to the hydrosilyl group-containing organopolysiloxane (C2) is determined appropriately depending on the composition ratio of the alkenyl groups and hydrosilyl groups. For example, 1 part by mass or more and 100 parts by mass or less of the hydrosilyl group-containing organopolysiloxane may be added per 100 parts by mass of the alkenyl group-containing organopolysiloxane, and preferably 10 parts by mass or more and 40 parts by mass or less.

[0093] (C3) Hydrosilylation catalyst The hydrosilylation catalyst is a metal catalyst used in the hydrosilylation reaction. Examples of such catalysts include platinum group metals such as platinum, rhodium, ruthenium, and palladium, and compounds thereof. Examples of platinum group metal compounds include platinum dichloride, platinum dibromide, platinum tetrachloride, chloroplatinic acid, alcohol-modified chloroplatinic acid, Karsted's catalyst (a complex of platinum and vinylsiloxane), sodium chloroplatinate, potassium chloroplatinate, bisacetylacetonatoplatinum, tetrakis(triphenylphosphine)palladium, and chlorotris(triphenylphosphine)rhodium. These may be used alone or in combination of two or more.

[0094] The content of the hydrosilylation catalyst may be any amount necessary for the curing reaction, for example, for 100 parts by mass of the total of (C1) and (C2), such as, for example, 0.01 part by mass or more, preferably 0.1 part by mass or more, and for example, 1 part by mass or less, preferably 0.5 part by mass or less.

[0095] The content of the silicone resin in the composition is, for example, 1 mass% or more, preferably 2 mass% or more, more preferably 5 mass% or more, and for example, 45 mass% or less, preferably 25 mass% or less, more preferably 10 mass% or less.

[0096] (D) Other Components The present composition preferably contains an alkoxysilyl group-containing compound from the viewpoints of increasing the affinity with the filler and the silicone resin and improving the flowability of the present composition.

[0097] Examples of the alkoxysilyl group contained in the alkoxysilyl group-containing compound include trialkoxysilyl groups such as trimethoxysilyl group, triethoxysilyl group, triisopropoxysilyl group, and triphenoxysilyl group; dimethoxysilyl groups such as dimethoxymethylsilyl group and diethoxymethylsilyl group; and monoalkoxysilyl groups such as methoxydimethylsilyl group and ethoxydimethylsilyl group. Preferably, trialkoxysilyl group is used, and more preferably, trimethoxysilyl group and triethoxysilyl group are used.

[0098] The alkoxysilyl group-containing compound is preferably a polysiloxane represented by the following formula (10).

[0099]

[0100] R ６ is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 10 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of hydrocarbon groups include R １ Examples of the groups include the same groups as those exemplified in the group 1. Preferably, an alkyl group is used, and more preferably, a methyl group or an ethyl group is used. ６ may be the same or different from each other.

[0101] R ７ is, for example, a hydrocarbon group, preferably a hydrocarbon group having 1 to 20 carbon atoms. These hydrocarbon groups may be substituted with a halogen atom or the like. Specific examples of hydrocarbon groups include R ２ Examples of the alkyl group include the same groups as those exemplified in 1. Preferably, an alkyl group is used, and more preferably, an n-butyl group or a methyl group is used.

[0102] R ８ is an alkoxysilyl group, as described above.

[0103] For example, k is a number of 0 or more and 100 or less, preferably 10 or more and 50 or less.

[0104] j is, for example, a number of 0 or more and 10 or less, preferably 1 or more, and preferably 8 or less, and more preferably 5 or less.

[0105] The content of the alkoxysilyl group-containing compound in the present composition is, for example, 0.1 mass% or more, preferably 0.3 mass% or more, and for example, 3 mass% or less, preferably 1 mass% or less.

[0106] When the silicone resin is a curable silicone resin, the composition preferably contains a reaction inhibitor to inhibit the curing reaction of the silicone resin. This inhibits the curing reaction of the composition before use, thereby improving storage stability. In addition, it inhibits a rapid curing reaction during use, thereby improving the workability of the composition when placed.

[0107] Examples of the reaction inhibitor include acetylene alcohol, benzotriazole, triphenylphosphine, and diallyl maleate, with acetylene alcohol being preferred. Examples of the acetylene alcohol include ethynyl-1-cyclohexanol and 2-methyl-3-butyn-2-ol. These may be used alone or in combination of two or more.

[0108] The content of the reaction inhibitor in the present composition is, for example, 0.01 mass% or more, preferably 0.03 mass% or more, and for example, 1 mass% or less, preferably 0.1 mass% or less.

[0109] The composition may contain other components in addition to those described above, as long as the effects of the present invention are not impaired. Examples of other components include a flame retardant, an antifoaming agent, a leveling agent, an antioxidant, and a colorant.

[0110] The present composition can be prepared by mixing (A) the present polysiloxane, (B) the filler, (C) the silicone resin (e.g., (C1) an alkenyl group-containing organopolysiloxane, (C2) a hydrosilyl group-containing organopolysiloxane, and (C3) a hydrosilylation catalyst), and, if necessary, other components, using a known method. For example, these components may be mixed simultaneously or in any suitable order.

[0111] The mixing can be carried out by a known method using a known mixing device such as a blender, a mixer, etc. If necessary, the mixing may be carried out in a heated atmosphere or an inert gas atmosphere.

[0112] The silicone composition of the present invention can suppress an increase in hardness of the silicone composition and its cured product when left at high temperatures (e.g., 100°C to 200°C) for long periods of time (e.g., 500 hours to 1500 hours). Furthermore, the composition has excellent fluidity, making it easy to apply and otherwise work with. The hardness increase suppression effect of the present invention is believed to be due to the following mechanism, but the present invention is not limited to this mechanism. Generally, in conventional silicone compositions highly loaded with fillers such as thermally conductive fillers, an interaction, which is a chemical reaction between hydroxyl groups on the filler surface and hydrosilyl groups on the silicone resin, occurs. This reaction proceeds over a long period of time at high temperatures, resulting in a continuous increase in the hardness of the composition. In contrast, the present composition contains the present polysiloxane having a dicarboxylate metal salt structure, and it is believed that the dicarboxylate metal salt portion interacts with the filler surface before the silicone resin does, inhibiting the interaction between the filler and the silicone resin. Furthermore, because this polysiloxane has a polysiloxane structure, it is similar to the silicone resin matrix resin and has good compatibility with the silicone resin, which is presumably why it can exist uniformly in the silicone resin and inhibit the above-mentioned interaction without phase separation.

[0113] The present composition may be in any form, but is preferably liquid, as long as it contains (A) the present polysiloxane, (B) a filler, and (C) a silicone resin. When the present composition is liquid, it may be a one-part or two-part composition. When the present composition is a two-part composition (first and second parts), the combination of components in the first and second parts is not limited. For example, when the present composition is an addition reaction type silicone composition containing an addition reaction type silicone resin, the present composition preferably contains (A) the present polysiloxane, (B) a filler, (C1) an alkenyl group-containing organopolysiloxane, (C2) a hydrosilyl group-containing organopolysiloxane, (C3) a hydrosilylation catalyst, and (D) a reaction inhibitor. In this case, it is preferable that the first or second part does not simultaneously contain the (C1) alkenyl group-containing organopolysiloxane and the (C2) hydrosilyl group-containing organopolysiloxane. For example, a combination of the first agent: (A) (B) (C1) (C3) and the second agent: (C2) (D), or a combination of the first agent: (A) (B) (C1) (C3) and the second agent: (A) (B) (C1) (C2) (D), etc. may be used.

[0114] The use of the present composition is not limited and can be used for a variety of purposes. In particular, when the composition contains a thermally conductive filler, it can be suitably used as a thermal interface material for efficiently dissipating heat generated from a semiconductor device to the outside. The present composition may also be used as a thermally conductive grease, a thermally conductive filler, a thermally conductive sheet, a thermally conductive adhesive, or the like. Furthermore, the present composition can also be used as part of a component of an electric or electronic device, including a semiconductor device.

[0115] (Electronic Components) Hereinafter, as one embodiment in which the present composition is used as a thermal interface material, a semiconductor device, which is an example of an electronic component, will be described with reference to FIG.

[0116] A semiconductor device 1 shown in FIG. 1 includes a printed wiring board 2 , an IC chip 3 which is an example of a heat generating member, a heat sink 4 which is an example of a cooling member, and a thermal interface material 5 .

[0117] The thermal interface material 5 is disposed between the IC chip 3 and the heat sink 4 so as to be in contact with them. The thermal interface material 5 is formed from the present composition. In particular, when the present composition is a curable silicone composition containing a curable silicone resin, the thermal interface material 1 is preferably a cured silicone product obtained by curing the curable silicone composition. That is, it is preferable to dispose the uncured curable silicone composition between the IC chip 3 and the heat sink 4 and then cure it. This allows the present composition to be disposed without any gaps between the IC chip 3 and the heat sink 4, allowing heat from the IC chip 3 to be more efficiently conducted to the heat sink 4. The curable silicone composition can be cured according to a known method, for example, by heating at a temperature of 80°C or higher and 200°C or lower.

[0118] 1, an IC chip 3 is shown as an example of a heat-generating member, but the heat-generating member may also be, for example, various semiconductor devices such as a power module, a transistor, etc. While a heat sink 4 is shown as an example of a cooling member, the cooling member may also be, for example, a housing or the like.

[0119] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0120] Synthesis Example 1 (Preparation of Single-Terminated Si—H Polysiloxane) 66.7 g of hexamethylcyclotrisiloxane and 50 g of cyclohexane were placed in a reactor equipped with a rotor and a nitrogen-filled gas bag, and then 19.2 mL of a hexane solution of n-butyllithium (1.57 mol / L) was added dropwise and stirred at 35°C for 2 hours. 20 g of THF was then added dropwise to this solution and stirred for 21 hours. 3.69 g of chlorodimethylsilane was then added dropwise and stirred for 2 hours. A 10% by weight aqueous solution of sodium bicarbonate was added to the resulting crude reaction liquid, causing it to separate into two layers, and the organic layer was washed with distilled water. This organic layer was dehydrated with magnesium sulfate, the solvent was removed using an evaporator, and the remaining volatile components were removed under conditions of 80°C and 100 Pa, yielding 60.0 g (85% yield) of the single-terminated Si—H polysiloxane shown below. The number of repeating units was: １ It is an average value determined from H-NMR.

[0121]

[0122] The obtained single-terminated Si—H polysiloxane １ The results of H-NMR measurement are shown below. １ H-NMR (500 MHz, solvent: CDCl ３ ) δ (ppm): 4.70 (1H, m, H-Si), 1.31 (4H, m, C-CH ２ CH ２ -C), 0.88 (3H, t, CH ３ -C), 0.53 (2H, m, Si-CH ２ ), 0.0 to 0.2 (144H, m, CH ３ -Si).

[0123] (Preparation of one-terminal succinic anhydride-modified polysiloxane) 50.0 g of the above one-terminal Si—H polysiloxane, 5.0 g of allyl succinic anhydride, 50 ml of toluene, and 5.4 mg of Pt catalyst (2 mass % xylene solution of Pt 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex) were placed in a reactor equipped with a Dimroth column and a thermometer, and stirred at 80° C. for 18 hours. The resulting crude reaction liquid was heated to 120° C., and volatile components were removed under reduced pressure (100 Pa), yielding 51.0 g (yield 95%) of the following one-terminal succinic anhydride-modified polysiloxane. The number of repeating units was １ It is an average value determined from H-NMR.

[0124]

[0125] The obtained polysiloxane modified with succinic anhydride at one end was １ The results of H-NMR measurement are shown below. １ H-NMR (500 MHz, solvent: CDCl ３ ) δ (ppm): 3.10 (1H, m, CH-CO), 2.5 to 2.8 (2H, m, CH ２ -CO), 1.3 to 1.8 (8H, m, Si-C-CH ２ CH ２ -C), 0.88 (3H, m, C-CH ３ ), 0.56 (4H, m, Si-CH ２ ), 0.0 to 0.2 (144H, m, CH ３ -Si).

[0126] The results of IR (ATR method) measurement of the obtained polysiloxane modified with succinic anhydride at one end are shown below and in Figure 2. IR (cm ―１ ): 2962 (C-H), 1865 (C=O), 1789 (C=O), 1257 (Si-CH ３ ), 1012-1078 (Si-O)

[0127] (Preparation of one-end lithium succinate-modified polysiloxane) 10 g of the above one-end succinic anhydride-modified polysiloxane, 0.67 g of lithium acetate, 50 mL of THF, and 1 mL of water were placed in a reactor equipped with a distillation apparatus and heated at 60°C for 2 hours. Subsequently, the temperature was raised to 80°C, and stirring was continued while distilling off THF and by-product acetic acid. After the distillation stopped, 50 mL of toluene was added to the reactor and heated at 125°C, and the acetic acid was removed by azeotropy with toluene. After the distillation stopped, toluene was added again, and the mixture was heated at 125°C until the distillation stopped. Next, volatile components were removed at 120°C under reduced pressure (100 Pa), and the following gel-like one-end lithium succinate-modified polysiloxane was obtained.

[0128]

[0129] The results of IR (ATR method) measurement of the obtained polysiloxane modified with lithium succinate at one end are shown below and in FIG. 3. IR (cm ―１ ): 2962 (C-H), 1611 (C=O), 1572 (C=O), 1258 (Si-CH ３ ), 1012-1078 (Si-O)

[0130] 2 and 3, it can be seen that lithium carboxylate is produced, since the C═O stretching vibration is shifted to the wave number derived from the metal carboxylate.

[0131] Synthesis Example 2 The following mono-terminal lithium succinate-modified polysiloxane was obtained in the same manner as in Synthesis Example 1, except that the amount of hexamethylcyclotrisiloxane charged was changed to 133.4 g.

[0132]

[0133] The results of IR (ATR method) measurement of the above-mentioned polysiloxane modified with lithium succinate at one end are shown below and in FIG. 4. IR (cm ―１ ): 2962 (C-H), 1611 (C=O), 1582 (C=O), 1258 (Si-CH ３ ), 1012-1078 (Si-O)

[0134] Synthesis Example 3 The following mono-terminal calcium succinate-modified polysiloxane was obtained in the same manner as in Synthesis Example 1, except that lithium acetate was replaced with calcium acetate monohydrate.

[0135]

[0136] The results of IR (ATR method) measurement of the polysiloxane modified with calcium succinate at one end are shown below and in FIG. 5. IR (cm ―１ ): 2962 (C-H), 1604 (C=O), 1564 (C=O), 1258 (Si-CH ３ ), 1012-1078 (Si-O)

[0137] Synthesis Example 4 20 g of 10-undecylenic acid and 20 g of toluene were placed in a reaction vessel equipped with a reflux condenser and heated to 80°C. 10.9 g of hexamethyldisilazane was added dropwise thereto, and after the completion of the dropwise addition, the mixture was heated at 80°C for an additional 3 hours. The mixture was heated to 100°C under reduced pressure to remove volatile components, and CH ２ =CH(CH ２ ) ８ CO ２ SiMe ３ (27.0 g, yield 97%). 6.37 g of the above silylated product, 50 g of the one-terminated Si—H polysiloxane prepared in [Synthesis Example 1], and 10 mg of Pt catalyst (2 mass % xylene solution of Pt 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex) were placed in a flask equipped with a reflux condenser and heated at 80°C for 2 hours. After cooling to room temperature, 10 g of methanol was added and the mixture was stirred at room temperature for 12 hours. The mixture was heated to 160°C under reduced pressure to remove volatile components and allowed to cool to room temperature to obtain the following one-terminated monocarboxylic acid-modified polysiloxane (52.7 g, yield 98%).

[0138]

[0139] [Synthesis Example 5] A reactor equipped with a distillation apparatus was charged with 10 g of the one-terminal monocarboxylic acid-modified polysiloxane prepared in [Synthesis Example 4], 0.30 g of lithium acetate, 50 mL of THF, and 1 mL of water, and heated at 60°C for 2 hours. The temperature was then raised to 80°C, and the mixture was stirred while distilling off the THF and by-product acetic acid. After the distillation stopped, 50 mL of toluene was added to the reactor, and the mixture was heated at 125°C to remove the acetic acid by azeotropy with toluene. After the distillation stopped, toluene was added again, and the mixture was heated at 125°C until the distillation stopped. Next, volatile components were removed at 120°C under reduced pressure (100 Pa), and the following gel-like one-terminal lithium monocarboxylic acid-modified polysiloxane was obtained.

[0140]

[0141] The results of IR (ATR method) measurement of the above-mentioned one-terminal lithium monocarboxylate-modified polysiloxane are shown below and in FIG. 6. IR (cm ―１ ): 2962 (C-H), 1579 (C=O), 1560 (C=O), 1258 (Si-CH ３ ), 1013-1078 (Si-O)

[0142] [Raw Materials] The following raw materials were used: Aluminum nitride (D ５０ : 120 μm, manufactured by Tokuyama Corporation) Aluminum nitride (D ５０ : 30 μm, manufactured by Tokuyama Corporation) Aluminum nitride (D ５０ : 1 μm, manufactured by Tokuyama Corporation) Alumina (D ５０ : 75 μm) Alumina (D ５０ : 1.5 μm) Alumina (D ５０ : 0.3 μm) Vinyl group-containing organopolysiloxane (structure shown below, viscosity (23° C.) 100 mPa·s)

[0143]

[0144] Hydrosilyl group-containing organopolysiloxane (structure shown below, viscosity (23°C) 50 mPa·s)

[0145]

[0146] Hydrosilylation catalyst (platinum metal) Alkoxysilyl group-containing polysiloxane (structure below (k=30), affinity agent)

[0147]

[0148] ・Reaction inhibitor (ethynyl-1-cyclohexanol) ・Lithium stearate

[0149] Examples 1 to 8 A silicone resin mixture was obtained by mixing 2.41 parts by mass of a vinyl group-containing organopolysiloxane, 0.60 parts by mass of a hydrosilyl group-containing organopolysiloxane, 0.01 parts by mass of a hydrosilylation catalyst, and 0.03 parts by mass of ethynyl-1-cyclohexanol. Next, the raw materials were mixed in the proportions shown in Table 1 below to prepare the liquid silicone compositions of Examples 1 to 8. The numbers in the table indicate parts by mass.

[0150] Comparative Examples 1 to 4 Liquid silicone compositions of Comparative Examples 1 to 4 were prepared by mixing the raw materials according to the formulations shown in Table 1 below.

[0151] [Evaluation of fluidity] The fluidity of the silicone compositions of each example and comparative example was evaluated as follows. The results are shown in Table 1. ◯: When each silicone composition was injected into a 30 cc syringe and discharged from a 2 mm diameter nozzle, the amount discharged per minute was 25 g or more. Δ: The amount discharged per minute was 15 g or more but less than 25 g. ×: The amount discharged per minute was less than 15 g.

[0152] [Evaluation of Initial Hardness] The silicone composition of each Example and Comparative Example was heated at 100°C for 2 hours so as to form a sheet having a thickness of 6 mm after curing. The hardness of the resulting cured silicone product was measured using a rubber hardness tester (Durometer GS-721G, TYPE-E, manufactured by Teclock Corporation). The results are shown in Table 1.

[0153] [Evaluation of hardness after long-term heating test] The above-mentioned silicone cured product was further heated at 150°C for 1000 hours, after which the hardness was measured. In addition, the difference (B - A) between the initial hardness A and the hardness B after the heating test was calculated. These results are shown in Table 1.

[0154]

[0155] It can be seen from Table 1 that the silicone composition of this example has good fluidity and therefore good workability in application, etc. Furthermore, compared with the silicone composition of the comparative example that does not contain this polysiloxane, the silicone composition of this example shows a reduced degree of change in hardness before and after the test, and therefore it can be seen that an increase in hardness is suppressed when left at high temperatures for a long period of time.

[0156] REFERENCE SIGNS LIST 1 Semiconductor device 2 Printed wiring board 3 Semiconductor chip 4 Heat sink 5 Present composition

Claims

1. A silicone composition comprising: (A) a linear organopolysiloxane having one dicarboxylic acid metal salt structure at the end of its main chain; (B) a filler; and (C) a silicone resin.

2. The silicone composition according to claim 1, wherein the structure of the metal dicarboxylate is a group represented by the following formula (1) or (2): (In formulas (1) and (2), M ｄ＋ represents an alkali metal ion or an alkaline earth metal ion. a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less. d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal. e is 2 when M is an alkali metal, and 1 when M is an alkaline earth metal. f is an integer of 0 or more and 10 or less, g is an integer of 0 or more and 5 or less, and h is an integer of 0 or more and 5 or less.

3. The silicone composition according to claim 1, wherein the content of the filler in the silicone composition is 70% by mass or more.

4. The silicone composition according to claim 1, wherein the filler is a thermally conductive filler.

5. The silicone composition according to claim 1, wherein the silicone resin is a curable silicone resin.

6. The silicone composition according to claim 5, wherein the curable silicone resin contains an alkenyl group-containing organopolysiloxane and a hydrosilyl group-containing organopolysiloxane.

7. A cured silicone product obtained by curing the silicone composition according to claim 5.

8. An electronic component comprising: a heat-generating member; a cooling member; and the silicone composition according to any one of claims 1 to 6 or the silicone cured product according to claim 7, which is placed in contact with the heat-generating member and the cooling member.

9. A polysiloxane compound represented by the following formula (5): (In formula (5), R １ represents a hydrocarbon group, and R ２ represents a hydrocarbon group; n is an integer of 1 or more and 100 or less; and A is a group represented by the following formula (1) or (2): (In formulas (1) and (2), M ｄ＋ represents an alkali metal ion or an alkaline earth metal ion. a is an integer of 0 or more and 10 or less, b is an integer of 0 or more and 3 or less, and c is an integer of 0 or more and 3 or less. d is 1 when M is an alkali metal, and 2 when M is an alkaline earth metal. e is 2 when M is an alkali metal, and 1 when M is an alkaline earth metal. f is an integer of 0 or more and 10 or less, g is an integer of 0 or more and 5 or less, and h is an integer of 0 or more and 5 or less.

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